/λ/ - programming

The compiler is gcc. I don't think it matters much to you which compiler you use and the only other option is clang.
Anyway, on most systems gcc is already installed, try at the terminal

$ cc --version

to see if you have it, if 'cc' fails try 'gcc'.
Else you just need to use the package manager on tails, of course I assume you already know how to do that. With 1000% certainty it's in the repos.
And to compile your file, say it's named hello.c

 
$ cc hello.c -o hello

or gcc, whatever. And run with

./hello

sudo apt-get install build-essentials

should install

gcc

which is the GNU C compiler: https://gcc.gnu.org/ It's the most widely used free software compiler.

OP here

None of this seems to work. I did download GCC a few days ago but unsure what to do with it… In other words how to manually install it.

>>187
Tails is not meant to be extended by more programs, nor usable in everyday usage.
If you insist on tails, you could build your own tails images.
But keep in mind that the torproject designed Tails carefully, to prevent the installed programs to give away your Identity.
The next problem is that you need to secure the computer, you would build your own version of Tails…
I hope it is clear that you do not want to do this.

1. https://qubes-os.org/ The better option, if you have the Hardware. 16GB RAM and an SSD really are useful.
2. Subgraph OS could be worth a shot. It is pretty fresh (that's bad), but promising.
3. plain Debian + Tor Browser should do nicely too, just pay attention and learn more on Linux.

>>188
Is it possible to run qubes off a thumbdrive?

For C and Unix, I'd probably recommend FreeBSD. It comes with a compiler and everything you need in the default install. Useful tools like ctags, yacc, lex, and so on
Maybe OpenBSD though: it comes with X in the default install, unlike FreeBSD.

>>194
No, take a closer look at the OS (such as reading up on it from the website) to get some real understanding. Tails is fully designed to work off of a usb or cd, qubes is fully designed to work on your computer as a main os.

>>194
yes. use Whonix with it too